Commit a247c3a9 authored Sep 22, 2010 by Andrea Arcangeli Committed by Linus Torvalds Sep 22, 2010

rmap: fix walk during fork



The below bug in fork led to the rmap walk finding the parent huge-pmd
twice instead of just once, because the anon_vma_chain objects of the
child vma still point to the vma->vm_mm of the parent.

The patch fixes it by making the rmap walk accurate during fork.  It's not
a big deal normally but it worth being accurate considering the cost is
the same.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent df08cdc7

kernel/fork.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -356,10 +356,10 @@ static int dup_mmap(struct mm_struct mm, struct mm_struct oldmm)
		if (IS_ERR(pol))
		goto fail_nomem_policy;
		vma_set_policy(tmp, pol);
		tmp->vm_mm = mm;
		if (anon_vma_fork(tmp, mpnt))
		goto fail_nomem_anon_vma_fork;
		tmp->vm_flags &= ~VM_LOCKED;
		tmp->vm_mm = mm;
		tmp->vm_next = tmp->vm_prev = NULL;
		file = tmp->vm_file;
		if (file) {

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